One issue here seems to be the understanding of "reasonable" force for a copper effecting an arrest (or the public in self defence). Too often, it is taken as minimum force. We need to reconsider this, and treat is as "as much force as you have a reason for". In other words, if you are single crewed and need to deck a guy in order to restrain him before his mates turn up, you should feel confident that your superiors will back you and if needs be you will be defended in court because you had a reason for your decision. Even if part of that decision was the shortage of other officers to back you up because of the ridiculous scale of spending cuts. (Notes that the need for austerity still doesn't seem to have extended to MP's expenses).